This invention relates to the decontamination of polluted soil wherein the soil is excavated and subsequently subjected to a thermal treatment.
Various methods are known for the decontamination of soil tainted with pollutants such as, for example, oil. The pollutants can be removed from the soil with, for example, the aid of a washing agent, e.g., water or a solvent. The resultant contaminated washing agent must, in turn, subsequently be processed by expensive methods, such as sedimentation, flotation, extraction, or distillation, in order to separate the pollutants. Substantial problems also arise in the separation of the washing agent from the soil. Usually, a large residue of contaminated washing agent will always remain in the soil.
Another soil decontamination method resides in the severe heating of the soil with flue gases and subsequent combustion of the pollutant-free gas mixture. However, this process can produce dioxins, thus requiring an expensive flue gas purification system.